1. Field of the Invention
The present invention relates to a constant temperature refrigeration system for extensive temperature range application and a control method thereof, more particularly, to a refrigeration system and a method for controlling such refrigeration system; such refrigeration system is for keeping working fluids under constant temperature, and such working fluids are utilized for manufacturing processes in semiconductor, biochemical material, food-processing and original material industries.
2. Description of Related Arts
Refrigeration equipment required by general manufacturing processes usually adopts a coolant compression refrigerator in cooperation with an electrical heating device for automatic compensation, thus achieving the dual functions of heating and cooling, and accurately maintaining the predetermined temperature of working fluids such as coolants, non-freezing liquids, brine or liquid mixtures for manufacturing processes.
The conventional constant temperature refrigeration system 2 is shown in FIG. 21, comprising a tank 20 having an input conduit 27 and an output conduit 28, a pump 26 connected in tandem with the output conduit 28, an evaporator 21 mounted in the tank 20 for providing cooling source, a heater 22 mounted in the tank 20 for providing heat source, a refrigerator connected in tandem with the evaporator 21, including a condenser 23, an inflation valve 24 and a compressor 25 for providing with the coolant loop. The input conduit 27 is for introducing the working fluid into the tank 20, whereas the output conduit 28 is then for outputting the working fluid having exactly the predetermined temperature required by manufacturing processes.
Since the conventional constant temperature refrigeration system 2 utilizes one set of cooling source to proceed to cooling and a set of heat source to proceed to heating compensation, for the evaporator 21 providing the cooling source and the heater 22 providing the heating source are both placed in the identical tank 20, no abnormal operation shall occur for the compressor 25 if applied in manufacturing processes or constant temperature control under smaller heat load. However, for applications under larger heat load for longer periods of time, the design of placing the cooling source and the heating source in the identical tank may easily cause abnormal actuation for high-temperature model compressors.
In addition, general refrigeration systems are usually designed for providing the environmental temperatures under certain low temperature ranges (such as −40° C. to 0° C.), as for applications requiring temperatures high than room temperatures (such as 60° C. to 100° C.), were low-temperature refrigeration systems utilized for maintaining the high-temperature cooling function, electricity shall be wasted, along with tremendous strain on the life time for the compressors because of the huge temperature differences; especially for apparatus in manufacturing processes required to run non-stop 24-hours per day for long periods of time, the energy put into such manufacturing processes shall surely be excessively wasted. For example, the vaporization temperature of the coolant in the conventional refrigeration system 2 shown in FIG. 21 is about −40° C. to 0° C., but if under high-temperature operation, the coolant drawn back to the compressor 25 shall be overheated to even reach 70° C. to 100° C., thus causing the conduit to be under high-pressure state for such overheated coolant is drawn therein, and then the efficiency for the compressor 25 to draw in the coolant is reduced to the extent that the coolant might not even be drawn smoothly back into the compressor 25, thus causing the refrigeration system 2 to lose the equilibrium and therefore the normal operation of the overall refrigeration system is endangered, a result shall cause serious delay of production.
Please refer to FIG. 1, which shows a constant temperature refrigeration system for extensive temperature range application, a U.S. application Ser. No. 10/331,991 owned by the Applicant. Such constant temperature refrigeration system for extensive temperature range application 10 comprises a refrigerator R, a low-temperature heat exchanger LHX, a medium-temperature heat exchanger MHX, a high-temperature heat exchanger HHX, a pump P, a first solenoid valve SV1, a second solenoid valve SV2, a third solenoid valve SV3, a temperature sensor TS1, a power regulator SSR and a controller C.
The medium-temperature heat exchanger MHX and the high-temperature heat exchanger HHX are both placed in a tank 11 mounted at the input end IN, and the tank 11, the pump P and the conduit of the output end OUT are connected in tandem with the first solenoid valve SV1, whereas the second solenoid valve SV2 is connected in tandem on the conduit of the medium-temperature heat exchanger MHX, and whereas the third solenoid valve SV3 is connected in tandem on the conduit of the low-temperature heat exchanger LHX while connecting in parallel with the first solenoid valve SV1. The refrigerator R is connected in tandem with the low-temperature heat exchanger LHX.
The power regulator SSR is electrically connected to the high-temperature heat exchanger HHX, an A.C. power source and the controller C, respectively. The temperature sensor TS1 is mounted in the controller C, which is electrically connected to the first solenoid valve SV1, the second solenoid valve SV2 and the third solenoid valve SV3, respectively, and the temperature sensor TS1 is connected to the input end IN and the output end OUT, so as to detect the temperature T2 of the input end IN and the temperature T1 of the output end OUT. The electrical connection circuits in drawings are represented by the dotted lines therein.
The power regulator SSR is to regulate the load of the high-temperature heat exchanger HHX, and the temperature sensor TS1 is utilized for predetermining the output temperature of the working fluid. The controller is utilized for controlling the first solenoid valve, the second solenoid valve and the third solenoid valve for conveying the fluid to various heat exchangers so that the working fluid is heated or cooled.
The working fluid can be coolants, non-freezing liquids, brine or liquid mixtures, and the working fluid is introduced in the tank 11 via the input end IN and outputted driven by the pump P through the first solenoid valve SV1 via the output end OUT, and through the third solenoid valve SV3 and the low-temperature LHX via the output end OUT.
The refrigerator R provides the cooling source below 25° C. for the low-temperature heat exchanger LHX. The facility water FW can be ice water with temperature thereof being higher than room temperature of 25° C., and such facility water FW flows through the second solenoid valve SV2 and the medium-temperature heat exchanger MHX so as to provide the medium temperature cooling source. The high-temperature heat exchanger HHX is constantly under “ON” state as the refrigeration system 10 is actuated, and the power regulator SSR is utilized for fine-tuning the temperature with reference to the temperature difference signals from the temperature sensor TS1, so as to provide temperature compensation.
The first embodiment of the controlling method on the refrigeration system 10 is elaborated in accordance with FIG. 1 to FIG. 7 as follows.
At first, the working fluid temperature required by the refrigeration system 10 is predetermined, then the pump P is actuated for inputting the working fluid and the facility water FW into the refrigeration system 10; the predetermined temperature, the actual inputting temperature T2 of the working fluid and the actual outputting temperature T1 of the working fluid from the temperature sensor TS1 are then read (since the predetermined temperature is set by the temperature sensor TS1, the predetermined temperature is represented by TS1) and compared, with the result of such comparison being utilized for heating or cooling the working fluid so as to cause the working fluid to reach the predetermined temperature.
More specifically, when comparing the predetermined temperature TS1, the actual inputting temperature T2 of the working fluid and the actual outputting temperature T1 of the working fluid, if T1 is higher than TS1, and TS1 is higher than T2, the cooling model is proceeded, at this time the difference between the outputting temperature T1 and the inputting temperature TS1 continues to be read to determine if such difference is smaller than the error value ε (+0.1° C. to −0.1° C.). If such difference is still larger than the error value ε, the cooling model then proceeds continuously; if smaller, the heating model is then employed instead such that the outputting temperature T1 of the working fluid is to reach the predetermined temperature TS1 so as to maintain the temperature of the working fluid under constant temperature state within the error value, which is shown in FIG. 7. No elaboration is required for other controlling models for comparing T1, TS1 and T2.
The foregoing cooling model and the heating model are elaborated further as follows by referring to FIG. 4 and FIG. 6 in accordance with FIG. 1.
As shown in FIG. 4, as the working fluid inputted is about to be cooled, the predetermined temperature TS1 is detected first, and then, as the refrigeration system 10 is for low-temperature application, the controller C is to switch the first solenoid valve SV1 as OFF, the second solenoid valve SV2 as OFF, the third solenoid valve SV3 as ON and the high-temperature heat exchanger HHX as ON, subsequently the working fluid is introduced into the tank 11 via the input end IN, then channeled by conduits to flow through the third solenoid valve SV3 and the low-temperature heat exchanger LHX, and eventually discharged through the output end OUT; as the refrigeration system 10 is for medium-temperature or high-temperature application, the controller C is to switch the first solenoid valve SV1 as ON, the second solenoid valve SV2 as OFF, the third solenoid valve SV3 as OFF and the high-temperature heat exchanger HHX as ON, subsequently the working fluid is introduced into the tank 11 via the input end IN, then channeled by conduits to flow through the first solenoid valve SV1 and eventually discharged through the output end OUT.
As shown in FIG. 6, as the working fluid inputted is about to be heated with the refrigeration system 10 being for low-temperature, medium-temperature or high-temperature application, the controller C is to switch the first solenoid valve SV1 as ON, the second solenoid valve SV2 as OFF, the third solenoid valve SV3 as OFF and the high-temperature heat exchanger HHX as ON, subsequently the working fluid is introduced into the tank 11 via the input end IN, then heated by the high-temperature heat exchanger HHX, and then channeled by conduits to flow through the first solenoid valve SV1 and eventually discharged through the output end OUT.
Shown in FIG. 2, the second embodiment of the constant temperature refrigeration system 10 for extensive temperature range application of the present invention comprises a refrigerator R, a low-temperature heat exchanger LHX, a medium-temperature heat exchanger MHX, a high-temperature heat exchanger LHX, a pump P, a first solenoid valve SV1, a second solenoid valve SV2 and a third solenoid valve SV3. The power regulator, the temperature sensor and the controller are all omitted in FIG. 2 for the means of electrical connections thereof are all identical to that in FIG. 1.
As shown in FIG. 2, the high-temperature heat exchanger HHX and the pump P are both mounted at the output end, with the conduit thereof being connected in tandem thereon with the first solenoid valve SV1, whereas the second solenoid valve SV2 is connected in tandem on the conduit of the medium-temperature heat exchanger MHX while connecting in parallel with the first solenoid valve SV1, and whereas the third solenoid valve SV3 is connected in tandem on the conduit of the low-temperature heat exchanger LHX while connecting in parallel with the first solenoid valve SV1.
The controlling method for the second embodiment of the constant temperature refrigeration system 10 for extensive temperature range application of the present invention is identical to that in FIG. 7 with the elaboration thereof being found in that of the first embodiment. However, the cooling model and the heating model of the second embodiment are elaborated further in accordance with FIG. 2, FIG. 5 and FIG. 6.
As shown in FIG. 5, as the working fluid inputted is about to be cooled, the predetermined temperature TS1 is detected first, and then, as the refrigeration system 10 is for low-temperature application, the controller C is to switch the first solenoid valve SV1 as OFF, the second solenoid valve SV2 as OFF, the third solenoid valve SV3 as ON and the high-temperature heat exchanger HHX as ON, subsequently the working fluid is introduced into the tank 11 via the input end IN, then channeled by conduits to flow through the third solenoid valve SV3, the low-temperature heat exchanger LHX and the high-temperature heat exchanger HHX, and eventually discharged through the output end OUT; as the refrigeration system 10 is for medium-temperature or high-temperature application, the controller C is to switch the first solenoid valve SV1 as OFF, the second solenoid valve SV2 as ON, the third solenoid valve SV3 as OFF and the high-temperature heat exchanger HHX as ON, subsequently the working fluid is introduced into the tank 11 via the input end IN, then channeled by conduits to flow through the second solenoid valve SV2, the medium-temperature heat exchanger MHX and the high-temperature heat exchanger HHX, and eventually discharged through the output end OUT.
As shown in FIG. 6, as the working fluid inputted is about to be heated with the refrigeration system 10 being for low-temperature, medium-temperature or high-temperature application, the controller C is to switch the first solenoid valve SV1 as ON, the second solenoid valve SV2 as OFF, the third solenoid valve SV3 as OFF and the high-temperature heat exchanger HHX as ON, subsequently the working fluid is introduced into the tank 11 via the input end IN, and then channeled by conduits to flow through the first solenoid valve SV1 and the high-temperature heat exchanger HHX, and eventually discharged through the output end OUT.
FIG. 3 shows the third embodiment of the constant temperature refrigeration system 10 for extensive temperature range application of the present invention, wherein the design is identical to that of the second embodiment except for the pump P and the high-temperature heat exchanger HHX being both mounted at the input end IN.
The controlling method for the third embodiment of the constant temperature refrigeration system 10 for extensive temperature range application of the present invention is identical to that of the first embodiment, so that it is not repeated herein. However, the cooling model and the heating model of the third embodiment are elaborated further in accordance with FIG. 3, FIG. 5 and FIG. 6.
As shown in FIG. 5, as the working fluid inputted is about to be cooled, the predetermined temperature TS1 is detected first, and then, as the refrigeration system 10 is for low-temperature application, the controller C is to switch the first solenoid valve SV1 as OFF, the second solenoid valve SV2 as OFF, the third solenoid valve SV3 as ON and the high-temperature heat exchanger HHX as ON, subsequently the working fluid is introduced into the tank 11 via the input end IN, then channeled by conduits to flow through the high-temperature heat exchanger HHX, the third solenoid valve SV3 and the low-temperature heat exchanger LHX, and eventually discharged through the output end OUT; as the refrigeration system 10 is for medium-temperature or high-temperature application, the controller C is to switch the first solenoid valve SV1 as OFF, the second solenoid valve SV2 as ON, the third solenoid valve SV3 as OFF and the high-temperature heat exchanger HHX as ON, subsequently the working fluid is introduced into the tank 11 via the input end IN, then channeled by conduits to flow through the high-temperature heat exchanger HHX, the second solenoid valve SV2 and the medium-temperature heat exchanger MHX, and eventually discharged through the output end OUT.
As shown in FIG. 6, as the working fluid inputted is about to be heated with the refrigeration system 10 being for low-temperature, medium-temperature or high-temperature application, the controller C is to switch the first solenoid valve SV1 as ON, the second solenoid valve SV2 as OFF, the third solenoid valve SV3 as OFF and the high-temperature heat exchanger HHX as ON, subsequently the working fluid is introduced into the tank 11 via the input end IN, and then channeled by conduits to flow through the high-temperature heat exchanger HHX and the first solenoid valve SV1, and eventually discharged through the output end OUT.
However, while under the medium temperature (25° C. to 50° C.) or high temperature (50° C. to 100° C.) as in FIG. 3, the cooling model thereof is that the first solenoid valve SV1 is in OFF mode, the second solenoid valve SV2 is in ON mode, and the third solenoid valve SV3 is in OFF mode, with the instant cooling process being completed via the facility water under 25° C. through the medium-temperature heat exchanger MHX. Yet, if the heat load of the working fluid becomes too high, the medium-temperature heat exchanger MHX then might fail to lower the temperature, which means when the heat load of the working fluid is greater than the heat exchanging capacity of the medium-temperature heat exchanger MHX, the temperature of the working fluid would be higher and higher without being able to be controlled under constant temperature. In addition, while under the low temperature (−40° C. to 25° C.), cooling model thereof is that the first solenoid valve SV1 is in OFF mode, the second solenoid valve SV2 is in OFF mode, and the third solenoid valve SV3 is in ON mode, which means the cooling process is completed by the low-temperature heat exchanger LHX. Yet since the 25° C. facility water is still kept in the medium-temperature heat exchanger MHX, as the control temperature is near the low temperature, the temperature of the facility water in the medium heat exchanger MHX would be lower and lower because of the heat conduction to the point where the control temperature is near −40° C., such that the temperature of the facility water in the medium heat exchanger MHX would be lower than 0° C., thus causing the facility water to be frozen so as to cause the medium-temperature heat exchanger MHX to cracks and damages.
In view of the object to improve upon the U.S. patent application Ser. No. 10/331,991, the present invention provides that a heat source is disposed at the outlet/inlet of the cooling end of the medium-temperature heat exchanger so as to interrupt the heat conduction of the working fluid during low temperature, thus preventing the temperature of the cooling water at the cooling end from being lowered to under 0° C., being frozen, and thus causing damages on the medium-temperature heat exchanger. Therefore, the present invention provides a more stable system and thus the time span for use of such system can be prolonged.